Low-water alarm



Sept. 18, 1928. 1,684,897

H. B. THURSTON v LOW WATER ALARM Filed July 16, 1926 4 Sheets-Sheet '1 lgwuantoz Gm: new

Sept. 18, 1928. 1,684,897 I v H. B. THURSTON I LOW WATER ALARM FiledJuly 16. 1926 4 Sheets-Sheet 2 1 v 6 m 5 4* v Mil/)1 6? Sept. 18, 1928.1,684,897

H. B. THURSTON LOW WATER ALARM Filed July 16. 1926- 4 Sheets-Sheet 4Fat-t nted Sort. 18,

siren STATES HERMAN B. THUR-STON, or

CLEVELAND HEIGHTS, OHIO.

LOVJ-WATER ALARM.

Application filed July 16,

This inv. ition relates to a low water alarm for steam boilers and theparticular adaptation is d gned for use with locomotive boilers. A veryessential result, necessary to the success of low water alarms is thatit shall sound when there is still water over the crown sheet or theboiler to enable the open ator to recoverthe normal water level, afterthe alarm has sounded, and before there is likelihood of any danger tothe crown sheet from o .'erheating.

.lleretotore. v numerous attempts have been made to accomplish thisresult, but the requirements for successful operation on a railroadlocomotive are very ditiicult to meet. t has been attempted to provide atime interval in the functioningof the alarm in order that it may notsound when only mon'ientarily subjected to low level of water.

in the previous applications of Herman 3. 'llh n 'ston, such forexample, as Serial No. 26.711, filed July 18, l92l,-and Frank M. doby,166,126, filed'March 19, 1925, it hasheen sought toaccomplish this bymeans of positioning a thermo-responsive alarm control within a certainzone, andcausing it to respond to an average water level irre spectiveof the surge of water and temporary displacement oi the level, bymeansof retarded thermal conductivity due to the alarm construction.

The present invention is designed on an en tirely diil'erent, and, Ibelieve, novel principle, whereby the alarm is responsive Veryaccurately to a water level-the average being accomplished by such atimeinterval by the definite and positive timing of flowing water,determining an arbitrary level of the water controlling the alarm. It iswell known that in stopping or even starting a locomotive, particularlyon grades, that for brief intervals the water level is radicallychanged-the body of the water level surging to one end of the boiler.This has made very diflicult the causing of alarm to function withcertainty, responsive to an average level of an 'inch or two inches overthe crown sheet. At the time when the level of water is approaching thedangerous low level, the fall is quite rapid and further adds to theditliculty of accomplishing the desired result. It has been demonstratedthat with the present invention. the alarm maybe caused to sound onlyunder actual conditions of danger, due to the tact that it is delayedsay, titty seconds or one minute after the water is below the 1926.Serial 1e.- 122,916.

critical point at which the alarm functions. lhe alarm will not sound itthe level is only temporarily dropped by surge of the water.

A further object ot' the invention is to so arrange such an alarm thatit may be accessible for easy and convenient inspection, cleaning andreplacement of parts. A still further object is to segregate a smallportion of the water where its surging movement, due

to the movement oi? the locomotive, ispractically eliminated so that theactuating means for the alarm may be independent of any water surgeeffect. 7

Other objects and advantages include the construction of such a device,so that it will be simple and certain in operation of its moving parts,and also such that the pro+ vision of a means for conveniently testingthe alarm may be provided. 7

Another outstanding advantage of the present low water alarm isthat'atter the alarm is sounded and'the dangerous condition has beeneliminated by the rise of the water level. the alarm automaticallyreconditions itself for further response without the attention of theoperator. This is an import-ant feature when compared to arrangements,having a fusible metal controlling the alarm, in which cases, it isusually necessary to remove parts of the alarm in order to replace thismetal. Therel ere, such former alarms would continue to sound as long asthere is steam'in the boiler after it had oncebeen actuated. Otheradvantagesand novel,characteristics will be made apparentin thefollowing description which relates to the drawings, illus trating apreferred emobdiment thereof. The essential novel characteristics aresummarized in the appendedclaims. v

In the drawings, Fig. l is a cross-sectional diagram of a locomotiveboiler, showing the position of this alarm device where usually mounted;Fig. 2 is an enlarged sectional detail of the outer sheet and crownsheet, carrying the alarm device, illustrating the relationship to thewater level; Fig. 3 is a plan,

of the alarm; Fig. 4 is an enlarged transverse section through the same,on a planeindicated by the line 4; -4 of Fig. 3;Fig. 5 is a longitudinalsection,tak en substantially on .a plane indicated by the line 5 -5 ofFig. 3; Fig. 6 1s a "section" taken longitudinally though the water tubeof the alarm, as indicated bythe line 6-6 of Fig. 4 Fig. 7 is asectional plan taken substantially on the line v-vor Fig. 4.

Fig. 8 is a sectiontaken on a plane indicated by the line El -8 of F 1g.4; Fig. 9 is an enlarged longitudinal section of the alarm valve andoperating means;

Fig. 10 is a sectional detail of the valve actuating means taken asindicated by the line '10-1O of Fig. 9.

ly to the chamber through thetube 6 having the inner extension 8.,leading substantially to the top of the chamber and projecting inwardly,preferably at an angle, as shown, to a point near the crown sheet andbelow the water level, indicated at W. I prefer to cut the lower end ofthe tube at right angles to the tube rather than in the plane of theabove the water in the reservoir whilethe bulk of the water in thereservoir will flow water level.

The shape of the reservoir is preferably that of a substantially flatcylinder, having an outer projecting cavity or chamber at 10 toaccommodate and allow for the necessary movement of a float 12,; whichoperates the alarm whistle, indicated at15, aswill be presentlydescribed. The main body of the res ervoir provides for a predeterminedcapacity of waterwhich may be drained through a comparatively smallopening near the lower part of the reservoir in the member 25. Thedownwardlyprojecting portion of the reservoir, as indicated at 11 isflanged with bracket members or ears 23 and is also pref: erablyprovided with a beveled surface 24 to provide a tight fit in the openingthrough the roof sheet. \Vithin this projection, I provide a securingmeans for the tube 6 in the nature of a member 25, held in threadedengagement. with the projection lland being threaded to receive the tube6, projecting upwardly from below and the extension tube 8, threadedinto the member from above.

A suitable cover may be provided for an opening in the upper portion ofthe reservoir, suitably secured as by screws and preferably providedwith a threaded boss to re ceive the removableplug 32 over the end ofthe tube 8 to permit convenient inspection of the tube. Depending fromthe cover 30, I provide a downwardly opening yoke 31 in vwhich the floatarm 42 may travel and be guided. 4 j j In line with the chamberportionltl, is a projection of the reservoir or casing, flanged toreceive cover member 35, which in turn, is threaded to receive the nut34.. On the innor side of the cover is preferably an into ral ear 39 asshown in Figs. 5 and 9, carrymg the pivot 40 for the float arm 42, whichin turn, is loosely connected zit/l4 to a longitudinally movable valvestem 45, actuating to close the steam passage in the valve member 36.The bell crank portion of the float armpreferably fits over the ear 39to assure a vertical swinging motion of the float arm.

In operation, assuming that the boiler is filled to a normal capacity ofwater, this level will be above thelower endsof the tube. As the steampressure rises water will be forced upwardly through the tube 6,'to thereservoir 5, forcing the air slowly through the alarm until the floatrises to close, the valve and thereafter, the level of water will risein the chamber, the air and steam above the water being compressed byboiler pressure until the chamber will be substantially full,maintaining the float buoyant for holding the alarm valve closed. V 1 17 When the water fallsbelow the lower end of the tube 6, the tube 6 willdrain quite quickly and steam passing upwardly through this tube willmaintain the boiler pressure comparatively slowly 20 in the member 25.will drain in proportion to the size of the opening 20 and the water inthe reservoir will through the opening start to lower while the waterlevel in the boiler exposes the end of the tube for a predeterminedtinie, say notless than a minute.

Then water in the reservoir will fall to. a

p unit where the float opens the valve by with drawing the valve stem45, allowing the steam through the tubes 6 and 8, now free of Water.

to pass from theboiler to the chamber and then, e through the valvepassages to the whistle,sounding the alarm. This flow of steam, soundingthe alarm, will continue as long as the water level in the boilerremains below the end of the tube.

It will be seen, however, that if,'due to a temporary surge of water,the lower end of the tube is exposed, the water in the reservoir willstart to drain but the alarm will not be sounded until the reservoir isemptied suiticiently to causethe float to fall and when the waterreturns again, covering the lower end of the tube, the boiler pressurewill cause an upward flow again, substantially filling the reservoirasjin the first instance. will be seen that by this means, we introduceintothe positive operation of an alarm, the time elementby apredeteri'nined rate of flow of a certain amount of water, through agiven orifice, to wit the opening 20. Thus thebot tom of the tube 6 mustbe exposed to steam for a predetermined lengthoftime or the equivalentto soundthe alarm. V

For purposes of testing the alarm at any therein outwardly,

The tube 6 therefore, I

ion

time, steam may be introducedinto the upper portion of the chamberthrougha pipe 60' valve 62.is closed except for test purposes. Uponopening the valve, the steam entering the top of the reservoir willrelease the hydrostatic head and permit the water to flow through theopening 20 until the float actuates the stem valve 45, causing the alarmto sound. Upon closing the hand valve 62, the reservoir again fills withwater as previously described, raising the float and closing the alarmvalve. It will be noted that the construction of the alarm valve is suchas to accommodate very convenient inspection, repair or replacement. Thefloat may be replaced or repaired by removal through the openings in thechambers. The tube 8 may be removed at any time through the openingclosed by the cover 30. This givesaccess to the lower tubes to keep themfree from boiler scale. The entire device may be very convenientlyremoved from the exterior. The arrangement of the tubes slantinginwardlyas shown, allows the device to be installed adjacent the steamdome if desired. and permits installation at a point'most convenient atthe exterior of the modern locomotive.

I claim:

l. The combination of a boiler having a steam space and a water space, alow water alarm comprising "a reservoir and a signal,

means responsive to water level and inclependent of temperature disposedwithin the reservoir for controlling-the actuation of the signal, saidreservoir being disposed exteriorly oi the boiler and above the waterlevel thereof, means for filling the reservoir when the water level inthe boiler rises above an established point and means for draining saidreservoir at a given rate when the water level falls below saidestablished point, whereby the alarm operates on successive occasions inresponse to a predeterminedcondition of low water.

a 2. A low water alarm comprising in combination a closed vessel adaptedto be secured to the exterior of the root sheet of a locomotive boilerat a point above the normal water level of the boiler, a conduitextending from the top of the vessel through the roof sheet and into theboiler and terminating at a point of dangerous water level in theboiler,

a float disposed within the vessel, a valve controlling the alarm, saidvalve being actuated by said float and means for successively drainingand filling the vessel to successively sound and silence the alarm.

3. The combination of a. boiler having a crown sheet and roof sheet, areservoir secured to the roof sheet above the normal water level of theboiler, a conduit extending to a point above the crown sheet oftheboiler at the level of dangerous low water and adapted to be sealed bywater of higher level, said conduit leading to the reservoir so that thereservoir is maintained full of water when the conduit is sealed by thewater in the boiler,

means for draining the reservoir when the conduit is unsealed, a floatin said reservoir, a valve actuated by said float for sounding an alarm,whereby the alarm may be successively sounded at each occurrence ofdangerous low water.

4. In a low water alarm, the combination of a boiler having a crownsheet and roof sheet, a closed vessel secured to the root sheet abovethe normal water level of the boiler, a conduit extending through theroot sheet to a point above and adjacent the crown sheet, said conduitleading to the vessel so that the vessel isiilled with water when theconduit is sealed by. the water in the boiler and drained when theconduit is unsealed, a duet in said vessel, a valve actuated by saidfloat :tor sounding-an alarm device whereby the alarm may besuccessively sounded whenever the vessel is drained.-

The combination of a boiler having a steam space and a water space, alow water alarm comprising a. reservoir and a signal, means responsiveto water level regardless of temperature disposed within the reservoirfor actuating the signal, said reservoir being disposed exteriorly oftheboiler and above the normal water level thereof, means for tilling thereservoir from theboiler when the water level .in the boiler rises abovean e tablished point and means for draining said reservoir at a givenrate when the water level falls below and remains below the establishedpoint, whereby the said signal will be successively actuated in responseto low water in the boiler after the level of the water in the reservoirfalls below a given hei 'ht for av given time. i

6. In combination with boiler having a steam space and water space, alow water alarm, comprising a signal and a. reservoir and adapted to bemounted on the boiler and having one passageway to the interior of theboiler and another to the signal, said reservoir being positioned abovethe normal water level of the boiler, the first passageway terminatingbelow the normal water level of the. boiler and means including a floatas sociated with the reservoir to control the actuation of the signaldependent upon the water level in the reservoir but independent of thepassageway.

"7. In combination,a boiler structure having a steam space and waterspace, a low water alarm, comprising a float controlled signal, areservoir for water to actuate the float, said reservoir being mountedabove the, normal water level of the boiler, a conduit having an openingterminating within the boiler at a point of dangerous low water leveland opening into the reservoir at the top thereof, and having a drainingopening within the reservoir, and means including a float associatedwith the reservoir responsive to predetermined amounts of water thereinby which to control the signal, whereby the. size of the drainingopening may determine the length of time required for the signal torespond after'the boiler water falls belowthe conduit boiler opening.

8. A method of operating a low water alarm for steam boilers, wherein apredetermined interval of time is obtained as the water in the boilerfalls below the danger point, including filling a small reservoir whichcontains a float for operating the alarm, said reservoir beingpositioned above the low water level of the boiler by raising water byboiler pressure through a passage active or inactive.

terminating at a danger level in the boiler, draining the water in thereservoir at a predetermined ratewhen the water falls below the terminusof the passage and causing the amount of water in the reservoir tocontrol the condition of the alarm by raising or low ering the float torender it successively either 9. In combination, a boiler having asteamspace and disposed exteriorly of the boiler and above the water level ofthe boiler, a float in said reservoir, a valve actuated by saidfloatandcontrolling an opening in the reservoir, a

conduit leading from the top portion of the reservoir through the bottomof thelreservolr into the boiler and terminating near the dangerouswater level therein, and being adapted to fill the reservoir wit-h waterwhen its lower terminus is sealed,"an orifice in the conduit within thereservoir and in the lower portion thereof, the orifice being of suchdimension that a given volume of water will pass through it in a'certaintime, whereby the seal- 1 in or unsealing of the terminus of the con- *2duit renders the alarm successively active or inactive.

' 10. Incombination, a boiler, a chamber disposed above the boiler, aconduit leading from the chamber to the interior of the boiler" andterminating below the normal water a water space, a closed reservoirlevel of the boiler, an alarm indicating member, and means mountedwithin the chamber and movable with reference thereto and adapted to beactuated by the rise and fall of water in the chamber for controllingthe operation of said member.

11. In combination, a boiler, a chamber disposed above the, boiler, aconduit leading from the chamber to the interior of the boil-' er andterminating below the normal water level oftheboiler, an alarmindicatingmemher, means within the chamber and adapted V to be moved withreference to the chamber by the rise and fall of water in the chamberfor controlling the operation of said'member, and

other means connected to the chamber and to a source of steam supply forenabling said flrstmentioned means to be actuated for operating saidmember under conditions sim ulating normaloperation thereof under lowwater conditions in said boiler.

12. The combination of a boiler, a chamber disposed at a hi mal waterlevel of t e boiler, a float in the chamber, an alarm signal, therebeing a valve disposed betweenthe chamber and the signal, said floatbeing arranged to closethe'valve when the float rises and to open thevalve when the float drops, and a conduitleading from the chamber intothe boilerto the low water level of the boiler. a

13. The combination of a boiler, a chamber disposed at a higher" levelthan the normal Water level of the boiler, a float in the chain HERMA B.THUnsToN;

her level thanthe nori

